Endless belts made from entirely thermoplastic, or fabric reinforced composite belts with thermoplastic ends for splicing, are well known in the art. Handrails such as those used with escalators also utilize an endless belt that is known to be spliced onto itself through thermoplastic welding. See for instance, U.S. Pat. No. 6,086,806 to Weatherall, et al., where a heated mandrel and a T-shaped mold are used to melt thermoplastic terminal portions of an endless belt. The melted ends of the thermoplastic material congeal together within the mold and form an integral structure.
Another prior art example is found in U.S. Pat. No. 6,234,304 to DeGroot et al. Free ends of thermoplastic material, such as polyurethane, are softened with a wand or other means and the softened ends are pressed together. The device of DeGroot is large, relatively non-portable, and difficult to control temperature wise. It also cannot operate using ordinary batteries for a power source.
U.S. Pat. No. 5,690,776, issued to Anderson, the entire disclosure of which is expressly incorporated herein, shows a belt splicing tool for thermally joining first and second ends of thermoplastic belts. The tool includes a position control means and first and second clamping mechanisms cooperatively engaged and diametrically opposed along a longitudinal axis. The first clamping mechanism holds a first end section of a belt and the second clamping mechanism holds a second end section of a belt. The position control means repositions the clamping mechanisms relative to one another along the longitudinal axis between a first position where the longitudinal spacing between the clamping mechanisms is minimized, and a second position where the longitudinal spacing between the clamping mechanisms is maximized. The tool retains and aligns both belt ends in an opposed abutting relationship while permitting longitudinal movement of the belt ends relative to one another. Splicing is accomplished by (i) placing the belt end sections in the tool, (ii) melting the end portion of at least one of the belts, and (iii) holding the end portions together until the material solidifies. Unlike the instant invention, however, no mechanism is provided as an integral part of the combination to weld the free ends of the belt together.
Many drawbacks are associated with the prior methods and devices for splicing thermoplastic belts. First, the devices are large and difficult to manage, particularly with smaller belts. Additionally the prior art devices do not securely clamp the free ends of the belt and simultaneously press them into a mechanical engagement while the softened thermoplastic interface congeals into a homogeneous weld. The prior art devices are relatively expensive as compared to the instant invention. Also the prior art devices have no mechanism to precisely control the area of heat application. None of the prior art devices operates using only an ordinary flashlight battery.
Basically, the prior art method involves heating the free ends across the entire surface of the free ends until they are softened as determined by visual inspection, and subsequently holding them together by hand until the free ends harden together as determined again by visual inspection.
Conventional devices use alternating 110 volt current from electrical outlets to weld belts together. Because food processing facilities must be constantly sterilized using such fluids as bleach, 110 volt outlets are impractical, since they are difficult to sterilize with fluids. For this reason, the prior art devices use long extension cords, usually wrapped on spools. The instant invention uses only battery power, and can be used on site without the need of 110 volt power. This saves not only time and considerable effort, but also affords easy storability of the device.